In the years after she drowned while scuba diving Australia's Great Barrier Reef. It seems no one can let go with Tina Watson. The -- mystery of the honeymooners death on the ocean floor captured in that terrifying photo deepens with each passing day. Friends and -- cannot rest. And neither can she. Within two years her widowed husband Gabe Watson has dug up Tina's body and moved her to another part of the cemetery. You've had holes body exhumed and moved -- why did you do that. It came up first with my grandmother then. -- -- -- -- And that's the state to finally caught. Did you tell Tina's family you're going to move her body and they they have -- since. Cut off communication they've started down their path of a murdered him and so there was no. That this was no talk between two things. Then the war of the grave -- roses Tina Stanley complaining someone shockingly is desecrating her grave. Taking the flowers and -- as they left for her. Even securing those arrangements with a bicycle lock doesn't work. Approximately. Eight radio so police set up a stink bomb a cemetery -- to. And right there armed with bolt cutters caught in the act is -- his own husband dean and why -- you do that. An investment when my finest hour home. I was still going through the grieving process. -- says Tina would have preferred the fresh flowers he always brought to the plastic flowers from her family they might be. Tacky nearest you that they were left by her the only who have terror. Why not respect that. I've just been accused of murder I mean they were out there telling people that I killed Tina for this massive large pictures -- I was still dealing with the death of Tina. I was -- I wasn't thinking clearly -- everything that I did he doesn't appear to be of grief stricken husband. So how do you think -- stricken husband should be acting. Grief stricken. -- -- that's how I think he should act. The ladies and -- returning the wedding presents. Maybe not desecrating her great. Being filmed desecrate her -- I don't think -- grief stricken husband would be. In his angering Tina Stanley -- fails to see it is not just to Dan who now suspect the worst. He is now a key suspect in a murder investigation spanning two continents. -- case being built so quietly they gave has no -- the police are coming for him until 2007. When they're on his doorstep. There's a knock at the door at 6 o'clock and open the door and there's all these armed FBI agents that come in and handcuffed me and someone else. That was the first time that a new songs and own and those -- ourselves. -- -- -- -- The FBI searches -- house on behalf of Australian police who conduct an inquest ended Tina's death for years after the fact. Police divers go so far as to reconstruct the fatal dive over the young -- shipwreck. Dramatizing their theory that Tina died not accidentally but at the hands of her husband. That moment when gates says he was with Tina trying to save her police now believe that's when he was actually killing her to see you -- -- Her to her reached around her and turned her -- off waited till she was dead and then turned it back on. What's reaction I mean that's a pretty. Horrific thing. I was pretty devastated. It was hard to imagine that. That there's someone out there that thinks. That that I did this so for the record did you kill Tina. Teacher turned her Arafat under water that day. He did nothing to harm her nothing intentional. And. Honeymoon killer gang Watson Watson and honeymoon killing guy on another front have been -- -- Watson. By now the story has the full attention of the media on two continents. Calling the case the honeymoon killer then in April 2008 after initially charging -- Watson with the murder. Australian authorities allow him to avoid a trial by pleading guilty to a far lesser crime. Negligent manslaughter. For abandoning his wife -- she struggled under the ocean. He is sentenced to just eighteen months in prison Tina's father can't believe it. -- -- They gave -- murdered our daughter. We'll continue to believe that this is not justice and this is an -- -- American lawyer is -- Livingston. Why would he plead guilty to manslaughter. Negligent manslaughter and Australia if you're innocent -- plead guilty. -- the law that that gave pled guilty to violating -- an obscure Australian law and it basically says that if you undertake a dangerous activity with someone. When you have a significantly. Higher standard or higher burden to ensure their safety you're -- guilty to failing to save Tina. I pled guilty to. They're basically. Not rendering the proper -- not. Not saving my -- -- in 2010 his prison term ending Gabe Watson's parents eagerly anticipate his return to the United States. But they're not the only ones Alabama prosecutors are waiting for him to. And -- got a grand jury indictment that could lead to life behind bars. When you got out of prison did you think okay nightmare over now coming on -- -- it was. Nightmare number to the state has -- -- kill her when we come back and Gabe Watson faces murder charges for a second time. And witnesses on the boat that today -- -- he's guilty he said she was too heavy and I lost my -- honor achievement hour. I said -- that's --

This transcript has been automatically generated and may not be 100% accurate.

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